This invention relates to switching power stages and amplifiers, and more particularly to a push-pull switching amplifier having zero output switching ripple.
Switching amplifiers based on the buck-type converter have been known in the past, but not widely used because of their deficiencies. A conventional buck-type amplifier will be described and some of its deficiences discussed. Then after the present invention disclosed herein has been described, a comparison of the invention with the prior-art switching amplifier will be made to reveal the superior characteristics of the invention.
The new switching amplifier is based on the new switching dc-to-dc converter disclosed in an application Ser. No. 837,532 filed Sept. 28, 1977 by Slobodan M. Cuk and Robert D. Middlebrook. That optimum topology converter is here used in a special bidirection implementation to provide a push-pull amplifier configuration. Hence all of the advantages of the new converter are obtained, such as high efficiency, small size and weight, and excellent dynamic performance, together with reduced pulsating for both input and output currents. The most important benefits, however, come from the use of the coupled-inductor technique of the new converter for the basic power stage in this special push-pull switching amplifier, which results in a high performance amplifier with complete elimination of the switching ripple in the output, one of the limitations in the conventional switching amplifier design. Thus, the new switching amplifier has potential for a wide range of applications from a high efficiency, small size and weight, and fast response servo power amplifier to a low-cost high-performance audio amplifier.